(1) Field of the Invention
This invention relates to an electromagnetic delay line combining an inductance element formed by a conductor winding and capacitors, and more particularly to improvements in and concerning an electromagnetic delay line which permits the selection of a delay time within a wide range, exhibits a rapid rise time and minimal distortion in the output waveform within the range of delay times and is suited for use in a digital circuit.
(2) Description of the Prior Art
Among conventional electromagnetic delay lines, there is known a delay line which has an inductance element formed by coiling a conductor in the shape of a single-layer solenoid on a bar-shaped bobbin. This inductance element is divided into a plurality of sections by interposing capacitors between the conductor and ground at intervals of a fixed number of turns of the coiled conductor of the inductance element.
In this electromagnetic delay line the delay characteristics thereof in terms of the quickness of rise time and the distortion of output waveform are improved by setting the coupling coefficient between the adjacent sections of the inductance element at a value on the order of 0.1 to 0.2, the coupling coefficient between sections separated by one intervening section at a value on the order of -0.02 to -0.03, the coupling coefficient of every successive odd-numbered section at a proper positive value, and the coupling coefficient of every successive even-numbered section at a proper negative value.
With the prior electromagnetic delay line constructed as described above, however, it has been difficult for the inductance element to obtain the optimum coupling conditions described above in an ultra-high frequency band, such as, for example, a band exceeding frequencies of 1 GHz. Thus, it has been accepted as infeasible that a delay line capable of producing a rise time not exceeding 1 ns could be obtained.
The present inventor has diligently studied this matter with a view to solving this difficulty. He has consequently found that the inductance element can be easily made to acquire the optimum coupling conditions in the ultra-high frequency band by elaborately coiling the conductor and suitably designing the configuration of the conductor of the delay line.